Climbing skins are used on snow to assist in travelling forward along flat ground or in ascending a slope on skis or using the separate “halves” of a split snowboard. The climbing skin is attached to the undersurface of the ski or snowboard half. Originally, climbing skins were made from the skins of animals. Modern climbing skins typically comprise a fabric containing synthetic and/or natural fibers with a pile surface comprising a nap. The nap is preferably unidirectional. When such material is adhered or otherwise attached to the undersurface of a ski or snowboard half with the pile facing the snow and with the nap predominantly angled rearwardly relative to the direction of travel, the ski or snowboard half may be slid in that direction with relative ease yet will resist opposite movement such as what occurs when the ski or snowboard half slips backwards on a hill. Through the use of climbing skins, a user can ascend a reasonably steep snow slope through use of a walking or shuffling motion.
The leading (forward) end of a climbing skin is typically attached at or near the forward end of a ski or snowboard half. A variety of means for such attachment are known, such as those referred to in U.S. 2010/0140901, including a pair of clips as disclosed therein.
A variety of means are known for attachment of the rearward end of a climbing skin at the tail or a ski or snowboard half. Examples are disclosed in DE8205601, U.S. Pat. No. 6,604,755, U.S. Pat. No. 6,471,234, CA2547416, and US 2010/0140901. DE8205601 discloses a flexible elastic connector joined to the rearward end of a climbing skin with a hook or other device for attachment to the tail of a ski. The elastic component can contain a pattern of elements intended to resist rearward slippage. Such elements are shaped like cups or scales and have a gripping surface or edges that face towards the device for attachment to the tail of the ski.
It is also known to modify the gliding characteristics of a climbing skin by incorporating materials other than pile. For example, U.S. Pat. No. 9,027,951 disclosed a climbing aid comprising at least one climbing aid section and a sliding section. The sliding section extends from an end that is connected to a tip of a ski over a section that corresponds to a ski longitudinal section of between 20% and 50% of the ski length and which contains the “bent-up” portion of the ski. The “bent-up” portion is the portion which contains the aforementioned forward convex region of the undersurface of the ski or snowboard. US 2008/0185817 discloses a series of stiff, longitudinally cambered or flat plates to be bonded to a ski base (the ski undersurface). The device includes an optional glide zone made of thin plastic or other slippery material which is bonded to the skin (or which replaces pile material of the skin) and is attached at or near the tip of a ski. Each plate requires at least one strap or snap for retention to the ski, preferably located at or near the centre of the plate. Other examples of climbing skins with glide zones can be found in CH637839, DE9304437 and WO2010/087721.
The use of plastic polymer sheets allows for construction of a climbing skin that absorbs little water and can have enhanced forward glide when a pile or other fabric surface is not present. An example is disclosed in WO2014/146159, an embodiment of which is sold under the trademark PROFOIL and is made from a plastic polymer sheet, with an adhesive surface over its entire length for adherence to the undersurface of a ski. Across the width of the sheet are discrete regions of elements, at least some of which resist backward slippage.
It is preferred for a climbing skin to bear an adhesive on its surface that is intended to face the undersurface of the ski or snowboard half. Various such adhesives are known in the art for this purpose. Such an adhesive is typically one that remains sticky at low temperatures and permits repeated attachment and removal of a climbing skin from the undersurface of the ski or snowboard half. Such climbing skins are referred to in this document as “glued climbing skins”. It is thought that the leading portion of a climbing skin that underlies the forward convex region of the undersurface of a ski or snowboard half should be adhered with such adhesive as best as possible without a gap (for example, see U.S. Pat. No. 9,027,951 at col. 7, lines 20 to 43). In order for the adhesive to remain sticky, the adhesive coated surface of the climbing skin should be kept clean and handled as little as possible. Snow building up on the adhesive surface will also reduce its adhesion to the ski or snowboard.
When in use, particularly in cold conditions, snow can creep between the glued climbing skin and the undersurface of the ski or snowboard resulting in loss of adhesion in that area, snow building up and the climbing skin peeling away from the ski or snowboard. This typically happens at the leading end of the climbing skin but also can occur at the rearward end.
It is desirable to reduce creeping of snow between a climbing skin and the undersurface of a ski or snowboard when in use, at least at the leading end.